The present invention relates to a device and a method of inspection of appearance of a filter rod used in manufacture of filter-tipped cigarettes.
A filter rod of this type includes a filter material made of a bunch of acetate fibers, and a sheet of paper for wrapping the filter material. The diameter of the filter rod is about 8 mm, and its length is in a range of 80 to 120 mm.
Such filter rod is first manufactured by a rod manufacturing machine, and supplied from the rod manufacturing machine into a filter feeder, then sent out from the filter feeder toward a filter-tipped cigarette manufacturing machine or a filter attachment with air stream in an air tube.
As known well, in the filter attachment, the filter rod is cut into four to six filter plugs, and each plug and two cigarettes are mutually combined by a tip paper piece, and a double filter-tipped cigarette is manufactured. Later, the double filter-tipped cigarette is cut off from the center of the plug, and individual filter-tipped cigarettes are obtained.
Since the filter rod is soft, the appearance of the filter rod is likely to have abnormality. Such appearance abnormality includes a bend of the filter rod, crush on the outer periphery of the filter rod, deformation of an end of the filter rod, a tear of the seam of the paper, etc.
Such appearance abnormality of the filter rod may further lead to a clogging of the filter rod in the filter feeder, the air tube or the filter attachment, or breakage of the filter rod and defective connection between the cigarettes and the plug in the filter attachment. The clogging of the filter rod may cause a shutdown of operation of the entire system from the filter feeder to the filter attachment, and the operation rate of the system is lowered. Such cutting and defective connection increase the number of defective filter-tipped cigarettes, and the productivity of filter-tipped cigarettes is lowered.
Accordingly, the defective filter rod having appearance abnormality should be eliminated from the system, and the appearance abnormality of the filter rod, therefore, must be inspected. However, since the filter rod are sent out at high speed from the filter feeder toward the filter attachment, it is not easy to develop a device and a method for inspecting the filter rods, individually.
It is hence an object of the present invention to provide an inspection device and an inspection method capable of inspecting appearance abnormality of a filter rod securely according to a simple principle of inspection.
The above object is achieved by the present invention. According to an inspection device and an inspection method of the present invention, a filter rod is fed along a conveying path, and contacted with a rolling surface in the conveying process so that a rolling force is applied to the filter rod. Thereafter, the inspection device and inspection method detect if the filter rod rolls on the rolling surface or not, and then determinate whether the filter rod is defective or not on the basis of the detection result.
In the case of a normal filter rod having no abnormality in appearance, when a rolling force is applied, the normal filter rod rolls easily. In the case of a defective filter rod having abnormality in appearance, even if a rolling force is applied, the defective filter rod does not roll. Accordingly, by detecting if the filter rod rolls or not in the conveying process of the filter rod, it is possible to determinate if the filter rod is defective or not. If the filter rod is defective, such defective filter rod is excluded from the conveying path.
For feeding filter rods, a rotatable inspection drum may be used. The inspection drum has a groove in the outer periphery thereof, the groove receiving one filter rod. The groove feeds the received filter rod while the inspection drum rotates. Further, the groove of the inspection drum has enough size for allowing rolling of the filter rod therein if the received filter rod is normal.
In this case, the aforesaid rolling surface may be defined at an inner surface of a rolling guide. The rolling guide extends along the outer periphery of the inspection drum, and partially covers the outer periphery. When the filter rod in the groove is fed while the inspection drum rotates, the filter rod receives a centrifugal force, and is pushed out toward the inner surface of the rolling guide. As a result, the filter rod contacts with the inner surface of the rolling guide, and securely receives the rolling force produced by the contact.
The inspection drum may be a grooved drum in the filter feeder or the filter attachment. More specifically, the inspection drum is preferred to serve also as a pickup drum for picking up filter rods one by one from a hopper in the filter feeder or the filter attachment. In this case, the inspection device can be easily assembled into the filter feeder or the filter attachment.
Rolling of the filter rod on the rolling surface can be detected by optically measuring a diameter of the filter rod. More specifically, means for measuring the diameter of the filter rod comprises a light emitter for emitting light toward the rolling surface and forming an illuminated region of light, the illuminated region being able to completely cover the filter rod with respect to the feeding direction of the filter rod, and a photo detector for measuring a shielded portion in the illuminated region by the filter rod while the filter rod is completely covered within the illuminated region of light and continuously outputting a measurement signal.
In this case, means for determining if the filter rod is rolling or not decides that the filter rod is normal when a ripple is contained in the measurement signal from the photo detector. This principle of the decision is based on the fact that a cross section of the filter rod, if normal, is not a complete round. That is, if the filter rod is rolling, the measurement signal indicating the diameter of the filter rod is not constant, but varies due to rolling of the filter rod, whereas if the filter rod is not rolling, the measurement signal is constant.